ORCA (Oscillations Research with Cosmics in the Abyss) is the low-energy branch of KM3NeT,the next generation underwater Cherenkov neutrino detector in the Mediterranean. Its primarygoal is to resolve the long-standing unsolved question of whether the neutrino mass orderingis normal or inverted by measuring matter oscillation effects with atmospheric neutrinos. TheORCA design foresees a dense configuration of KM3NeT detection units, optimised for studyingthe interactions of neutrinos in seawater at low (< 100 GeV) energies. To be deployed atthe French KM3NeT site, ORCA’s multi-PMT optical modules will exploit the excellent opticalproperties of deep seawater to accurately reconstruct both cascade (mostly electron neutrinos)and track events (mostly muon neutrinos) with a few GeV of energy. This contribution discussesthe potential of the ORCA detector both in neutrino mass ordering studies and in obtaining newconstraints on other key parameters such as theta_23. New sensitivity studies of exotic oscillationphenomena such as sterile neutrinos and non-standard interactions are also presented